Foldable force sensing device

ABSTRACT

A force sensing device includes a sensor array, a first substrate, a second substrate and a plurality of electrodes. The first substrate has a sensor region and a side region. The second substrate has a sensor region and a side region. The sensor array is formed above the sensor region of the first substrate. The plurality of electrodes are formed on the sensor region and the side region of the first substrate and below the sensor region and the side region of the second substrate, and coupled to the sensor array. The side region of the first substrate, the side region of the second substrate and the plurality of electrodes on the side region are foldable to a back side of the sensor array.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The disclosure relates to force sensing devices, and in particular, to afoldable force sensing device.

2. Description of the Prior Art

There has been a growing interest in providing frameless or seamlessarray devices in recent years. An array device such as a sensor arraytypically employs a considerable number of signal lines to controloperations of pixels in the sensor array. Conventionally, these signallines would take finite space at the side regions of the array device toconnect between an operational array and a controller, resulting in aproblem of designing a frameless or seamless structure of the arraydevice.

SUMMARY OF THE INVENTION

According to one embodiment of the invention, a force sensing deviceincludes a sensor array, a first substrate, a second substrate and aplurality of electrodes. The first substrate has a sensor region and aside region. The second substrate has a sensor region and a side region.The sensor array is formed above the sensor region of the firstsubstrate. The plurality of electrodes are formed on the sensor regionand the side region of the first substrate and below the sensor regionand the side region of the second substrate, and coupled to the sensorarray. The side region of the first substrate, the side region of thesecond substrate and the plurality of electrodes on the side region arefoldable to a back side of the sensor array.

According to another embodiment of the invention, a tiled deviceincludes a controller and a plurality of force sensing devices. Theplurality of force sensing devices are tiled with each other. Each forcesensing device includes a sensor array. The sensor array includes amatrix of pixels arranged at fixed vertical intervals and at fixedhorizontal intervals. The controller is arranged at back sides of sensorarrays of the plurality of force sensing devices, and is coupled to theplurality of force sensing devices.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are schematic diagrams of a force sensing device in anunfolded position according to an embodiment of the invention.

FIG. 2 is a cross-sectional view of the force sensing device in FIG. 1Aalong a line 2-2′.

FIG. 3 is a cross-sectional view of the force sensing device in FIG. 1Aalong a line 3-3′.

FIG. 4 is a cross sectional view of the force sensing device in FIG. 1Aalong a line 4-4′.

FIG. 5 is a schematic diagram of the force sensing device in FIG. 1A ina folded position.

FIG. 6 is a cross-sectional view of the force sensing device in FIG. 5along a line 6-6′.

FIG. 7 is a cross-sectional view of the force sensing device in FIG. 5along a line 7-7′.

FIG. 8 is a cross-sectional view of a pixel of the sensor array in FIG.1A.

FIG. 9 is a schematic bottom view of a tiled device according to anembodiment of the invention.

FIG. 10 is a schematic top view of the tiled device in FIG. 9.

DETAILED DESCRIPTION

FIG. 1A is a schematic diagram of a force sensing device 1 in anunfolded position according to an embodiment of the invention. FIG. 1Bis an enlarged view of a left side region of the force sensing device 1.FIG. 1C is an enlarged view of a bottom side region of the force sensingdevice 1. The force sensing device 1 may be arranged in a foldedposition or an unfolded position. During semiconductor fabrication, theforce sensing device 1 may be formed in the unfolded position. Later,the force sensing device 1 may be folded in the folded position to forma seamless or frameless device. A plurality of the seamless devices maybe tiled together along any edge of the seamless devices to form alarger tiled device.

Referring to FIG. 1A, the force sensing device 1 may be a pressuresensor, and may include a sensor array 10, a first substrate 11, asecond substrate 13, a plurality of first electrodes 120 to 12N, aplurality of second electrodes 140 to 14M, and a plurality of firstinsulation layers 150 to 15N, a plurality of second insulation layers170 to 17M and a controller, N, M being positive integers, and N, Mbeing identical to or different from each other.

The first substrate 11 may have a sensor region and a side region, thesensor region being the area of the first substrate 11 above which thesensor array 10 is formed, and the side region being a side area of thefirst substrate 11 above which no sensor array 10 is formed. The firstelectrodes 120 to 12N may be formed on the sensor region and the sideregion of the first substrate 11. The side region of the first substrateand the first electrodes 120 to 12N on the side region are foldable to aback side of the sensor array 10, thereby forming a seamless structurewhen folded back. Similarly, the second substrate 13 may have a sensorregion and a side region, the sensor region being the area of the secondsubstrate 13 below which the sensor array 10 is formed, and the sideregion being a side area of the second substrate 13 below which nosensor array 10 is formed. The second electrodes 140 to 14M may beformed on the sensor region and the side region of the second substrate13. The side region of the second substrate 13 and the second electrodes140 to 14M on the side region may be foldable to the back side of thesensor array 10, thereby forming the seamless structure when foldedback. The first electrodes 120 to 12N on the sensor region of the firstsubstrate 11 and the second electrodes 140 to 14M on the sensor regionof the second substrate 13 may be substantially perpendicular to eachother.

The sensor array 10 may include an array of sensing pixels 8 arranged atfixed vertical intervals and at fixed horizontal intervals to maintain afixed sensor pitch between the sensing pixels 8 along the verticaldirection and the horizontal direction. Each sensing pixel 8 may be madeof a force sensitive material. In one embodiment, N, M may both be 18,and the sensor array 10 may include an array of 19×19 sensing pixels 8.

The first substrate 11 and the second substrate 13 may be made of arigid material, a flexible material or a combination thereof. The firstsubstrate 11 may have a thickness less than 200 um, and the secondsubstrate 13 may have a thickness less than 200 um. The first electrodes120 to 12N and the second electrodes 140 to 14M may be made of aconductive material such as a metal or an alloy. The first substrate 11may be a bottom substrate, and the second substrate 13 may be a topsubstrate arranged above the first substrate 11. The first electrodes120 to 12N may be bottom electrodes, and the second electrodes 140 to14M may be top electrodes.

Referring to FIG. 1B, on the left side region of the force sensingdevice 1, the first substrate 11 may have a plurality of openings 161 to16N arranged in a column, the first electrodes 120 to 12N may be formedon the first substrate 11 and coupled to the sensor array 10 throughgaps between the plurality of openings 161 to 16N, the second substrate13 may have a slit S1 formed above the plurality of openings 161 to 16Nand gaps between the plurality of openings 161 to 16N, respectively, andthe plurality of first insulation layers 150 to 15N may be formed acrossthe slit S1, between the first electrodes 120 to 12N and the secondsubstrate 13 and between the plurality of openings 161 to 16N,respectively. In one example, a first insulation layer 15 n may beformed across the slit S1, between the first electrode 12 n and thesecond substrate 13, and between the openings 16 n and 16(n+1), n beinga positive integer between 1 and N−1. The plurality of first insulationlayers 150 to 15N may prevent the first electrodes 120 to 12N from beingexposed to the external environment and ensure the normal operations ofthe first electrodes 120 to 12N. The first electrodes 120 to 12N may becoupled to the sensor array 10 and the controller, and the controllermay detect a force applied to the sensor array 10 according to signalsdelivered by the first electrodes 120 to 12N. The force sensing device 1is foldable along the plurality of openings 161 to 16N and the slit S1.When being folded, the plurality of openings 161 to 16N and the slit S1may effectively reduce a bending stress owing to the fold, resulting ina compact and seamless structure, enhancing flexibility of tiling aplurality of the force sensing devices 1, without affecting the sensorpitch and operations of sensing pixels 8 in the proximity to the foldand signal delivery of the first electrodes 120 to 12N.

Referring to FIG. 1C, on the bottom side region of the force sensingdevice 1, the second substrate 13 may have a plurality of openings 181to 18M arranged in a row, the second electrodes 140 to 14M may be formedon the second substrate 13 and coupled to the sensor array 10 and thecontroller through gaps between the plurality of openings 181 to 18M,the first substrate 11 may have a slit S2 formed below the plurality ofopenings 181 to 18M and gaps between the plurality of openings 181 to18M, respectively, and the plurality of second insulation layers 170 to17M may be formed between the second electrodes 140 to 14M and the firstsubstrate 11, across the slit S2, and between the plurality of openings181 to 18M, respectively. In one example, a second insulation layer 17 nmay be formed across the slit S2, between the second electrode 14 n andthe first substrate 11, and between the openings 18 m and 18(m+1), mbeing a positive integer between 1 and M−1. The plurality of secondinsulation layers 170 to 17M may prevent the second electrodes 140 to14M from being exposed to the external environment and ensure the normaloperations of the second electrodes 140 to 14M. The second electrodes140 to 14M may be coupled to the sensor array 10 and the controller, andthe controller may detect a force applied to the sensor array 10according to signals delivered by the second electrodes 140 to 14M. Theforce sensing device 1 is foldable along the plurality of openings 181to 18M and the slit S2. When being folded, the plurality of openings 181to 18M and the slit S2 may effectively reduce a bending stress owing tothe fold, resulting in a compact and seamless structure, enhancingflexibility of tiling a plurality of the force sensing devices 1,without affecting the sensor pitch and operations of sensing pixels 8 inthe proximity to the fold and signal delivery of the second electrodes140 to 14M.

While the plurality of openings 161 to 16N are formed between all thefirst electrodes 120 to 12N in the force sensing device 1, it would beappreciated that the plurality of openings may also be formed betweensome of the first electrodes 120 to 12N to meet specific designrequirements. Likewise, while the plurality of openings 181 to 18M areformed between all the second electrodes 140 to 14M in the force sensingdevice 1, it would be appreciated that the plurality of openings mayalso be formed between some of the second electrodes 140 to 14M to meetspecific design requirements.

FIG. 2 is a cross-sectional view of the force sensing device 1 along aline 2-2′ in FIG. 1A. The cross-sectional view in FIG. 2 includes thefirst substrate 11, the first electrode 12 n, the first insulation layer15 n, the second substrate 13 and the slit S1 in the unfolded position.The first substrate 11, the first electrode 12 n, the first insulationlayer 15 n and the second substrate 13 are sequentially stacked on eachother from the bottom to the top. The first electrode 12 n is fabricatedon a surface of the first substrate 11 to secure the connection betweenthe sensor array 10 and the controller. The first insulation layer 15 nis deposited on the first electrode 12 n to prevent the first electrode12 n from being exposed to the external environment and ensure propersignal delivery of the first electrode 12 n. The slit S1 is formed atthe second substrate 13 to relieve the bending stress when being folded.

FIG. 3 is a cross-sectional view of the force sensing device 1 along aline 3-3′ in FIG. 1A. The cross-sectional view in FIG. 3 includes thefirst substrate 11, the opening 16 n, the second substrate 13 and theslit S1 in the unfolded position. Since no electrode passes through thethis part of the force sensing device 1, the opening 16 n is formed atthe first substrate 11, and the slit S1 is formed at the secondsubstrate 13 to significantly relieve the bending stress. Thecross-sectional view at an opening 18 m at the bottom side region of theforce sensing device 1 in FIG. 1C may be similar to FIG. 3, except thatthe opening 16 n is replaced with the slit S2 and the slit S1 is replacewith the opening 18 n, the configuration reduces the bending stressconsiderably when the force sensing device 1 is folded along theplurality of openings 181 to 18M and the slit S2.

FIG. 4 is a cross sectional view of the force sensing device 1 along aline 4-4′ in FIG. 1A. The cross-sectional view in FIG. 4 includes thefirst substrate 11, the slit S2, the second insulation layer 17 m, thesecond electrode 14 m and the second substrate 13 in the unfoldedposition. The first substrate 11, the second insulation layer 17 m, thesecond electrode 14 m and the second substrate 13 are sequentiallystacked on each other from the bottom to the top. The slit S2 is formedat the first substrate 11 to relieve the bending stress when beingfolded. The second insulation layer 17 m is deposited on the secondelectrode 14 m to prevent the second electrode 14 m from being exposedto the external environment and ensure proper signal delivery of thesecond electrode 14 m. The second electrode 14 m is fabricated on asurface of the second substrate 13 to secure the connection between thesensor array 10 and the controller.

FIG. 5 is a schematic diagram of the force sensing device 1 in a foldedposition, showing the first electrodes 120 to 12N, the second electrodes140 to 14M and the controller 50. Accordingly, the first electrodes 120to 12N may be folded back along the plurality of openings 161 to 16N andthe slit S1 to the back of the force sensing device 1 and coupled to thecontroller 50. Likewise, the second electrodes 140 to 14M may be foldedback along the plurality of openings 181 to 18M and the slit S2 to theback of the force sensing device 1 and coupled to the controller 50. Thefolding configuration ensures a compact and seamless structure, ensuringproper operations of sensing pixels 8 in the proximity to the fold andensuring signal delivery of the first electrodes 120 to 12N and thesecond electrodes 140 to 14M, and enhancing flexibility of tiling aplurality of the force sensing devices 1.

FIG. 6 is a cross-sectional view of the force sensing device 1 along aline 6-6′ in FIG. 5. The cross-sectional view in FIG. 6 includes thefirst substrate 11, the first electrode 12 n, the first insulation layer15 n, the second substrate 13 and the slit S1 in the folded position.When the force sensing device 1 is folded along the plurality ofopenings 161 to 16N and the slit S1, the slit S1 may be used to relievethe bending stress of the second substrate 13 and the first insulationlayer 15 n may protect the first electrode 12 n from being exposed.

FIG. 7 is a cross-sectional view of the force sensing device 1 along aline 7-7′ in FIG. 5. The cross-sectional view in FIG. 7 includes

the first substrate 11, the slit S2, the second insulation layer 17 m,the second electrode 14 m and the second substrate 13 in the foldedposition. When the force sensing device 1 is folded along the pluralityof openings 181 to 18M and the slit S2, the slit S2 may be used torelieve the bending stress of the first substrate 11 and the firstinsulation layer 17 m may protect the second electrode 14 m from beingexposed.

FIG. 8 is a cross-sectional view of a sensing pixel 8 of the sensorarray 10. The sensing pixel 8 includes the first substrate 11, the firstelectrode 12 n, the force sensitive material 80, the second electrode 14m, the second substrate 13 and adhesion 82. The first substrate 11, thefirst electrode 12 n, the force sensitive material 80, the secondelectrode 14 m, the second substrate 13 are sequentially stacked on eachother. The adhesion 82 may adhere between the first substrate 11 and thesecond substrate 13. The force sensitive material 80 may be made of apiezoelectric material, a piezoresistive material or a piezo-capacitivematerial.

FIG. 9 is a schematic bottom view of a tiled device 9 according to anembodiment of the invention, and FIG. 10 is a schematic top view of thetiled device 9. Four force sensing devices 1 are tiled together to formthe tiled device 9. The first electrodes 120 to 12N and the secondelectrodes 140 to 14M of the four force sensing devices 1 may be coupledto the same controller or different controllers. Since the firstelectrodes 120 to 12N and the second electrodes 140 to 14M of each forcesensing device 1 are folded back to provide the seamless structure, thesize of the tiled device 9 is not limited to the routing areas of thefirst electrodes 120 to 12N and the second electrodes 140 to 14M, andmay be expanded along any direction and to any desired size. Theplurality of pixels in each force sensing device 1 are arranged into amatrix at fixed vertical intervals wv and at fixed horizontal intervalswh. Each of the force sensing devices 1 is folded back along therespective openings 161 to 16M and slit S2 and along the respectiveopenings 181 to 18M and slit S2, adjacent pixels between verticallyadjacent force sensing array devices 1 of the plurality of force sensingdevices are arranged at the fixed vertical intervals wv, and adjacentpixels between horizontally adjacent force sensing array devices 1 ofthe plurality of force sensing devices are arranged at the fixedhorizontal intervals wh, resulting in a fixed pitch between adjacentpixels of the tiled device 9 along the vertical direction and thehorizontal direction, regardless of the pixels being in the proximity tothe edge or the center of the force sensing devices 1. Further, while2×2 sensor tiles are employed in the embodiment, other shapes and sizesof the tiled device may also be implemented using the seamless structureof the force sensing device 1.

While the first electrodes 120 to 12N and the second electrodes 140 to14M in FIGS. 1A to 1C, 5 and 8 are collected at the central part of theside regions, it would be appreciated that the first electrodes 120 to12N and the second electrodes 140 to 14M may also be collected at oneend of the side regions without interfering with each other when folded.For example, the first electrodes 120 to 12N may be collected at the topend of the left side region and the second electrodes 140 to 14M may becollected at the right end of the bottom side region. In this manner,the first electrodes 120 to 12N and the second electrodes 140 to 14M maynot interfere with each other when folded, while delivering the desiredseamless structure.

While the force sensing device 1 has been implemented as a sensordevice, those skilled in the art would appreciate that by applying thesimilar principle the foldable structure of the force sensing device 1may be adopted in other frameless devices or tiled devices, e.g., aframeless display device or a tiled display device.

The various embodiments of the force sensing device 1 in FIGS. 1A to 1C,2 to 6 provide a compact and seamless device structure while ensuringproper operations of sensing pixels 8 in the proximity to the fold andensuring proper signal delivery of the first electrodes 120 to 12N andthe second electrodes 140 to 14M, and enhancing the flexibility oftiling a plurality of the force sensing devices 1.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A force sensing device comprising: a firstsubstrate having a sensor region, a side region, and a plurality ofopenings; a sensor array formed above the sensor region of the firstsubstrate; a plurality of first electrodes formed on the sensor regionand the side region of the first substrate, and coupled to the sensorarray through gaps between the plurality of openings of the firstsubstrate; a second substrate having a sensor region and a side region,and having a slit formed above the plurality of openings of the firstsubstrate and the gaps between the plurality of openings of the firstsubstrate, the sensor region of the second substrate being above thesensor array; and a controller coupled to the first electrodes; whereinthe side region of the first substrate and the plurality of firstelectrodes on the side region are foldable to a back side of the sensorarray.
 2. The force sensing device of claim 1, further comprising: aplurality of first insulation layers formed between the first electrodesand the second substrate, across the slit of the second substrate, andbetween the plurality of openings of the first substrate.
 3. The forcesensing device of claim 1, wherein the force sensing device is foldablealong the plurality of openings of the first substrate and the slit ofthe second substrate.
 4. The force sensing device of claim 1, wherein:the second substrate further has a plurality of openings; the firstsubstrate further has a slit formed below the plurality of openings ofthe second substrate and gaps between the plurality of openings of thesecond substrate; and the force sensing device further comprises: aplurality of second electrodes formed on the sensor region and the sideregion of the second substrate, and coupled to the sensor array and thecontroller through the gaps between the plurality of openings of thesecond substrate; and a plurality of second insulation layers formedbetween the second electrodes and the first substrate across the slit ofthe first substrate, and between the plurality of openings of the secondsubstrate.
 5. The force sensing device of claim 4, wherein the forcesensing device is foldable along the plurality of openings of the secondsubstrate and the slit of the first substrate.
 6. The force sensingdevice of claim 4, wherein the plurality of first electrodes on thesensor region of the first substrate are substantially perpendicular tothe plurality of second electrodes on the sensor region of the secondsubstrate.
 7. The force sensing device of claim 1, wherein the sensorarray is made of a piezoelectric material.
 8. The force sensing deviceof claim 1, wherein the sensor array is made of a piezoresistivematerial.
 9. The force sensing device of claim 1, wherein the sensorarray is made of a piezo-capacitive material.
 10. The force sensingdevice of claim 1, wherein the sensor array comprises a plurality ofpixels each comprising a force sensitive material formed between acorresponding first electrode and a corresponding second electrode. 11.The force sensing device of claim 10, wherein the plurality of pixelsare arranged into a matrix at fixed vertical intervals and at fixedhorizontal intervals.
 12. The force sensing device of claim 1, whereineach of the pixels comprises adhesion configured to adhere between thefirst substrate and the second substrate.
 13. A tiled device,comprising: a plurality of force sensing devices tiled with each other,each force sensing device of the plurality of force sensing devicescomprising: a sensor array, the sensor array comprising a matrix ofpixels arranged at fixed vertical intervals and at fixed horizontalintervals; a first substrate having a plurality of openings; a pluralityof first electrodes arranged at a back side of the sensor array, formedon the first substrate and coupled to the sensor array through gapsbetween the plurality of openings of the first substrate; and a secondsubstrate having a slit formed above the plurality of openings of thefirst substrate and the gaps between the plurality of openings of thefirst substrate; and a controller arranged at the back sides of thesensor arrays of the each force sensing devices, and coupled to theplurality of first electrodes of the each force sensing devices; whereinadjacent pixels between vertically adjacent force sensing array devicesof the plurality of force sensing devices are arranged at the fixedvertical intervals; and adjacent pixels between horizontally adjacentforce sensing array devices of the plurality of force sensing devicesare arranged at the fixed horizontal intervals.
 14. The tiled device ofclaim 13, wherein the plurality of first electrodes of the each forcesensing devices are foldable to the back side of the sensor array of theeach force sensing device.
 15. The tiled device of claim 13, wherein theeach force sensing devices further comprises: a plurality of firstinsulation layers formed between the first electrodes and the secondsubstrate, across the slit of the second substrate, and between theplurality of openings of the first substrate.
 16. The tiled device ofclaim 13, wherein the each force sensing devices is foldable along theplurality of openings of the first substrate and the slit of the secondsubstrate.
 17. The tiled device of claim 13, wherein: the secondsubstrate further has a plurality of openings; the first substratefurther has a slit formed below the plurality of openings of the secondsubstrate and gaps between the plurality of openings of the secondsubstrate; and the each force sensing devices further comprises: aplurality of second electrodes formed on the second substrate andcoupled to the sensor array of the each force sensing device and thecontroller through the gaps between the plurality of openings of thesecond substrate; and a plurality of second insulation layers formedbetween the second electrodes and the first substrate across the slit ofthe first substrate, and between the plurality of openings of the secondsubstrate.
 18. The tiled device of claim 13, wherein the each forcesensing devices is foldable along the plurality of openings of thesecond substrate and the slit of the first substrate.
 19. The tileddevice of claim 13, wherein the sensor array of the each force sensingdevice is made of a piezoelectric material, a piezoresistive material ora piezo-capacitive material.